Ear bud earphones which are inserted into users' ear canals during use have become increasingly popular for use with portable media devices and mobile phones. One of the reasons for the popularity of these earphones is because they are able to isolate the external noises which adversely affect the sounds emanating from the earphones.
However, it is for this reason that the use of such earphones is hazardous to the user under certain conditions. Such earphones are typically able to isolate noise within a certain bandwidth by more than 20 dB. When the user is using such earphones while jogging or cycling outdoors, this isolation may detrimentally reduce the user's awareness to ambient/environmental conditions, and this lack of awareness because of the noise isolation may lead to the safety of the user being compromised. For example, the user may be unaware that a vehicle is approaching or the user may take a longer than usual duration to react appropriately to the approach of a vehicle.
Despite the hazards mentioned earlier, many users still continue with the use of such earphones while exercising outdoors. This is because it has often become a habit which is difficult to break. Thus, there is a need to have earphones with adjustable isolation levels for use in different usage scenarios.
In addition, such insert earphones typically introduce “microphonic” noise which is generated from conduction of cables to our ear. This effect is also heard when there is conduction between our skulls and jaw during movement of the jaw. This “microphonic” noise may also be reduced with the use of earphones with adjustable isolation levels.